Learning and development are central problems of current neuroscience research. The rapid progress of recent years has made three important themes clear. First, learning and development are closely related. They depend to a considerable extent on similar or identical molecular and synaptic processes. Second, both are in large part driven by certain types of neuronal activity occuring at specific sites, and at crucial times. Third, it is now possible for the first time to discuss in a connected and logical fashion the full sequence of events responsible for learning and development. Furthermore, such treatment is essential to progress beyond the fragmentary knowledge that has prevailed up to the present. These three themes are the impetus and the framework for this conference, which is the third on this topic sponsored by SUNY since 1980. The sequence of six half-day sessions will parallel the progression from neuronal activity to altered behavior. Thus, the first describes activity- driven triggers of plasticity, the second treats subsequent molecular events, the third and fourth discuss the resulting synaptic changes, and the fifth and sixth describe the expression of these changes in altered behavior. Throughout the meeting, the close relations between learning and development will be emphasized and analysed. This logical and comprehensive treatment, which has become possible only very recently, should distinguish this meeting. The conference will bring together leading scientists working on each aspect o the problem, from the neurotransmitter receptors triggering change to the patterns of activity causing altered behavior. Its six sessions, each focusing on a specific level of analysis, are: I. Excitatory Amino Acid Receptors as Triggers of Plasticity II. Molecular Mechanisms of Activity-driven Plasticity III. Silent Synapses IV. Activity-driven Anatomical Changes V. Expression of Plasticity in the Behavior of Hippocampal Circuitry VI. Expression of Plasticity in the Behavior of Intact Animals The meeting is designed to have maximum educational impact. Participants, besides speakers, will consist primarily of postdoctoral fellows and graduate students. A poster session is included. Full proceedings will be published.